Parkinson's disease and Dementia with Lewy bodies (DLB) together comprise the second most common form of dementia after Alzheimer's Disease (AD). The signature pathologic lesions in these disorders are Lewy bodies (Lbs) found in cortical (DLB) and nigral (PD) neurons. Furthermore, a significant number of AD patients develop parkinsonian signs during the course of disease and many of these patients also are found to have Lbs on autopsy. Whether previously diagnosed with PD- associated dementia now would be classified as DLB is unknown. It is also unclear that PD alone can cause dementia occurs only in the presence of critical Lbs or AD-related pathology. The goal of this project is to characterize the clinicopathologic phenotypes of Dementia of the Parkinson Type (DPT). We propose to analyze the longitudinal studies of the Alzheimer's Disease Research Center (ADRC) for the clinical, motor, cognitive, behavioral, and pathologic characteristics of autopsy defined case of AD, PD and DLB in order to: 1) determine those clinical features that differentiate pathologically diagnosed DLB and PD from AD and from each other to establish the DPT phenotype; 2) identify differences between groups in pathologic features other than those used in the diagnosis by exploring the neuroanatomical correlates of the unique clinical symptomatology of DPT; and 3) to determine the best short set of clinical features for the diagnosis of pathologically defined DPT groups. The ADRC and the Department of Neurology at Washington University School of Medicine provide the candidate with an outstanding environment to develop his skills as an independent clinician-scientist. This K08 award will make available to the candidate protected time to complete the Specific Aims of the project and complete didactic courses in the ethical conduct of research, biostatistics and epidemiological study design. The research career development plan of the candidate is to use the mentored period to establish in the field of dementia research, specifically examining the role co-existent pathologies play in the onset, progression and unique characteristics of dementing disorders. At the completion of the award period, candidate plans to develop an independent R01 project derived from the data generated by the experiments described in this proposal.